The invention relates to a sunless tanning cream effective as a self tanning formulation and in camouflaging the effects of vitiligo on human skin.
Millions of people desire efficacious products to camouflage skin imperfections as well as the effects of leukodermic conditions such as vitiligo. In addition, many of the same people also want tanned skin. Despite the well documented negative effects of long-term exposure to ultraviolet light, global populations generally equate tanned skin with health and affluence. Present sunless tanning products have proven inadequate to serve the above needs of consumers, particularly African American consumers, due to inadequate match of skin tone and poor functional longevity.
It would be advantageous to provide a sunless tanning cream that effectively provides the appearance of tanned skin without having to go into the sun. It would be even more advantageous if such a cream would produce an immediate tanned appearance and last for an extended period of time.
Furthermore, it is desirable that such a sunless tanning cream, in addition to effectively tanning healthy skin of people in the general population, would also effectively camouflage the unsightly effects of vitiligo. Vitiligo is a chronic depigmentation disorder that causes unsightly white patches or splotches on the patient""s skin. These splotches are caused by localized depigmentation at discrete sites over the skin surface. Vitiligo affects people of all ethnicities and races. However, its effects are particularly pronounced in African American patients due to the high contrast between their natural brown or black skin and the bright white splotches characteristic of vitiligo.
While the patient suffers no debilitating effects from vitiligo, it often can have a negative psychological impact, particularly in African Americans for the above reason. Consequently, a number of creams have been developed primarily comprised of a makeup base which do not medically treat the vitiligo, but are designed to mask its effects by camouflaging the depigmented splotches.
However, current makeup-based creams, e.g. Dermablend, Coverblend, and Dermacolor, suffer from a number of drawbacks in their application. Specifically, existing creams mask white splotches for only limited periods of time before washing or rubbing off. Consequently, such creams must be applied at least daily to provide any lasting benefit to the wearer. In addition, existing creams have an objectionable feel on the skin which is unpleasant to the touch. Existing creams also tend not to be well matched to the various skin tones of African American vitiligo patients.
Consequently, there is a need in the art for a sunless tanning cream that provides a lasting tanned appearance, and that successfully masks the effects of vitiligo for an extended period of time in a manner that cannot be washed or rubbed off. Preferably, such a cream would not be objectionable to the touch, and would be well matched to the skin tone of the wearer, particularly for African Americans.
A sunless tanning formulation is provided which comprises a non-makeup cosmetic and a coloring system. The coloring system comprises a makeup. The non-makeup cosmetic is effective to darken the epidermis via a chemical reaction. Also provided is a sunless tanning formulation that is effective to camouflage the effects of vitiligo when applied to skin. The formulation is a water-in-oil emulsion having an inner water phase and an outer oil phase, and comprises an effective amount of dihydroxyacetone, a coloring system comprising oil-soluble and water-soluble coloring agents, an emulsifying system effective to provide a water-in-oil emulsion, and a solvent system comprising silicone-based solvents.
A method of camouflaging the effects of vitiligo is also provided. The method comprises the step of applying an effective amount of DHA to a depigmented splotch on a patient""s skin.
A method of providing the appearance of tanned skin is also provided. The method comprises step of applying a sunless tanning preparation to the skin, wherein the preparation has a makeup and dihydroxyacetone. The makeup provides an immediate coloring effect yielding the appearance of tanned skin, while the dihydroxyacetone undergoes a chemical reaction with the epidermis to provide a lasting appearance of tanned skin after the makeup has washed away.
As used herein, when a range such as 5-25 or between 5 and 25 is given, this means preferably at least 5 and, separately and independently, preferably not more than 25. Also as used herein, xe2x80x9ccosmeticxe2x80x9d means any component or substance that improves the general appearance of skin, thus yielding a xe2x80x9ccosmetic effect.xe2x80x9d A xe2x80x9ccosmetic effectxe2x80x9d means the effect of improved skin appearance through application or use of a xe2x80x9ccosmetic.xe2x80x9d
As used herein, the term xe2x80x9cmakeupxe2x80x9d means a cosmetic in the form of a pigment, dye, or other colored material, whose sole function is to create the appearance of color when applied to the skin, the apparent color being that of the xe2x80x9cmakeupxe2x80x9d itself. As used herein, xe2x80x9cnon-makeup cosmeticxe2x80x9d means a cosmetic that is not in the form of a pigment, dye, or other similar colored material that creates the appearance of color when applied to the skin, the apparent color being that of the pigment, dye or other similar colored material.
The invented formulation is provided preferably in the form of a cream, less preferably as a gel, spray or aerosol, less preferably in some other known form applicable to the skin. The formulation is effective in camouflaging the unsightly white splotches characteristic of vitiligo, particularly in African American patients. The formulation is dispensed preferably from a soft tube, less preferably from a jar, bottle, pump, can, spray can or spray bottle, less preferably from some other known container.
The invented formulation has the preferred compositions of components shown in table 1 below. It should be noted that table 1 defines four separate preferred embodiments of the invention. The four preferred embodiments differ in the color of their respective cosmetic effects (light brown, brown, dark brown, and honey), with each of the preferred embodiments differing primarily in the most preferred concentrations of the coloring system components. The four preferred formulations are substantially similar in other respects. In table 1, any preferred or less preferred weight percent or weight percent range of any component can be combined with any preferred or less preferred weight percent or weight percent range of any of the other components; it is not required or necessary that all or any of the weight percents or weight percent ranges come from the same column. The column labeled xe2x80x9cPhasexe2x80x9d refers to the preferred order and method of mixing the components, and is explained in detail below. Unless otherwise specified, all concentrations are weight percents.
The formulation contains a non-makeup cosmetic, preferably dihydroxyacetone (DHA), in an amount effective to darken the epidermis via a chemical reaction as is known in the dermatologic art, thus yielding a true cosmetic effect. Less preferably, other known non-makeup cosmetics which darken the epidermis via a chemical reaction can be used. The formulation also contains a makeup, preferably a combination of multiple makeups, collectively referred to herein as the coloring system. Preferably, the invented formulation further contains a solvent system and an emulsifying system.
The invented formulation preferably is provided as a water in oil emulsion, with the water phase being the internal phase and the oil phase being the external phase. The emulsifying system is effective to accomplish this purpose. The emulsifying system preferably comprises emulsifiers, preferably PEG esters, that are compatible with DHA. Compatible emulsifiers are not prone to hydrolysis and preferably have a low pH, preferably 4-7, more preferably 5-6, most preferably about 5.5. Compatible emulsifiers also preferably have no functional amino groups, particularly no primary amino groups. Preferably, the emulsifying system comprises PEG-30 dipolyhydroxystearate, sorbitan isostearate, dimethicone copolyol beeswax, and decyl glucoside, less preferably PEG esters of triglycerides and/or low ethoxylate nonionic surfactants. Less preferably, the emulsifying system comprises ethoxylated alcohols and/or glycerol esters.
The solvent system preferably comprises at least one silicone-based solvent, most preferably the following silicone-based solvents: cyclopentasiloxane with dimethicone copolyol, cyclometicone, and dimethicone. Preferably, the solvent system also contains an emollient ester such as diisodecyl adipate in a quantity effective to abate the objectionable feel and improve the spreadability of the silicone-based solvents over the skin. Diisodecyl adipate also aids solubilization of oil-soluble makeup components in the silicone phase. Other suitable emollient esters include isopropyl myristate, decyl oleate, and other emollient esters known in the art which are effective to improve spreadability and feel. Such a preferred silicone-based solvent system has been shown to provide an outer emulsion phase that spreads easily and evenly over the skin, has little or no objectionable feel, and effectively solvates oil-based makeup components for good color longevity. Less preferably, other silicone-based solvents can be used. Even less preferably, other non-silicone based solvents capable of solvating oil-soluble color components may be used in the oil phase. Silicone-based solvents are generally preferred because they provide a formulation that has high wearability, and is aesthetic in appearance compared to other non-silicone based solvents.
The coloring system preferably contains both water-and oil-soluble makeup components. Preferably, the water-soluble makeup components comprise at least one or a mixture of DandC and/or FDandC coloring agents as are known in the art. Preferably, the oil-soluble makeup components comprise at least one or a mixture of natural pigments, synthetic pigments, plant extracts, fruit extracts, vegetable extracts, and/or other oil-soluble makeup components as known in the art.
Preferably, the invented formulation also contains sodium chloride as an emulsion stabilizer as well known in the art, and an antimicrobial agent such as Germaben II from ISP, Inc. The antimicrobial agent serves as a preservative to kill bacteria and fungus that may be introduced into the product during consumer use.
It should be noted that each of the coloring system components in table 1 is provided as a solution having a concentration of that component of the weight percent indicated. For example, DandC Violet #2 is provided as a 1% solution of DandC Violet #2 in mineral oil. Therefore, a sunless tanning formulation comprising 0.4 wt. % concentration of the DandC Violet #2 solution would actually comprise 0.004 wt. % DandC Violet #2. A similar calculation is required to determine the absolute weight percent of each of the coloring system components in the invented formulation.
Optionally, the invented formulation contains a volatile emulient in place of diisodecyl adipate and dimethicone in the solvent system to provide a quick drying formulation. The volatile emulient evaporates quickly from the skin thus providing a formulation that dries at an accelerated rate. The volatile emulient is preferably isododecane, preferably Permethyl 99A from Presperse, Inc., and is present in the invented formulation at a concentration of 0.5-20, preferably 1-15, preferably 1.5-10, preferably 2-5, preferably about 2.5, wt. %. Isododecane can be substituted for diisodecyl adipate and dimethicone in any of the four preferred color variants of the invented formulation as embodied in table 1 (honey, light brown, brown, and dark brown) to provide a quick drying equivalent. A quick drying formulation according to the present invention dries preferably in less than 180, preferably 120, preferably 100, preferably 80, preferably 60, preferably 45, preferably 30, seconds following application to the skin. The formulation is considered xe2x80x9cdryxe2x80x9d when it no longer feels slippery or wet on the skin.
The unique combination of oil-and water-soluble color components provides a formulation that instantly camouflages the effects of vitiligo upon application to the skin, while the DHA undergoes a chemical reaction with the epidermis to provide a more long-lasting effect even after the skin has been thoroughly cleansed. The water-soluble color components (makeups) present in the inner water phase of the emulsion instantly color the skin upon application. The oil-soluble color components present in the outer silicone phase of the emulsion, in combination with the chemical effects of DHA, provide a more balanced long-term camouflage of vitiligo splotches that is color-matched to the patient""s individual skin tone.
The invented formulation is also effective as a self tanning preparation or self tanner. When used as a self tanner, the user applies a quantity of the formulation to the skin in a conventional manner where a tanning effect is desired. Similarly as above, the coloring or make-up components provide an immediate darkening or coloring effect giving the appearance of tanned skin. In the meantime, the DHA reacts with the underlying epidermis to yield a lasting tanned appearance once the make-up components have been washed away. In this manner, a more balanced long-term and color-matched tanning effect is provided.
As indicated above, the invented formulation is in the form of a unique water in oil emulsion, with the water phase being the inner phase and the oil phase (silicone phase) being the outer phase. This water-in-oil system is uncommon in existing sunless tanning creams because DHA solubilizes in the water phase, and therefore water is most commonly the external phase in order to facilitate rapid DHA absorption into the skin. However, a major disadvantage to existing oil-in-water emulsions is that DHA experiences significant atmospheric degradation upon contact with oxygen present in ambient air. Such atmospheric degradation significantly depletes the efficacy of existing sunless tanning creams. However, the water-in-oil emulsion system of the present invention provides a more stable environment for the DHA because atmospheric oxygen does not easily penetrate the outer oil phase to transcend the oil-water phase boundary and attack the DHA within the inner water phase. Though DHA present in an inner water phase will be absorbed, and therefore react to tan the skin, more slowly, a delayed DHA reaction is inconsequential because the makeup color components in the invented formulation provide an instantaneous color effect. Specifically, the makeup components yield the appearance of a color effect while the DHA reaction takes place in the epidermis beneath to provide a lasting color effect.
A second disadvantage of oil-in-water emulsions of present tanning creams is that the external water phase contains water-soluble color components that are easily washed away or distorted from sweat, humidity, splashing, and the like. Such a sunless tanning cream comprising DHA thus could be effectively washed off before the DHA has even absorbed into the skin. The water-in-oil emulsion system of the present invention solves this problem by providing an external oil phase that is hydrophobic. A hydrophobic external phase results in a formulation that is much more resistant to washing away from sweat, humidity, or otherwise upon contact with water before the DHA has been absorbed into the skin. A sunless tanning formulation according to the present invention, applied in a conventional manner, will provide effective camouflage of vitiligo splotches or the appearance of tanned skin for at least 24, preferably 36, preferably 48, preferably 60, 72, 84, 96, or 108, hours.
With reference to table 1, the invented formulation is preferably prepared as follows. First, the components of phase A are combined and mixed together while heating to 75xc2x0 C. Next, the components of phase B are combined, mixed together, and separately heated to 50xc2x0 C. Third, the components of phase C are added to the phase B mixture and mixed together to form a heterogeneous mixture of substantially uniform composition at 50xc2x0 C. The combined phase B/C mixture is added to the phase A mixture with vigorous agitation at 75xc2x0 C., with the resulting mixture vigorously agitated until a sunless tanning formulation having a substantially uniform composition of all components is formed. The sunless tanning formulation is allowed to cool, and is then packaged for use. The invented formulation is applied to the skin in a conventional manner.